<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="">
<script>
function changeImage()
{
element=document.getElementById('myimage')
if (element.src.match("bulbon"))
  {
  element.src="pic_bulboff.gif";
  }
else
  {
  element.src="pic_bulbon.gif";
  }
}
</script>

<img id="myimage" onclick="changeImage()"
src="pic_bulboff.gif" width="100" height="180">

<p>Click the light bulb to turn on/off the light</p>
</form>
</body>
</html>